#left {
  margin-right: 153px;
}
#right {
  margin-left: 150px;
}

#left_wrapper {
  width: 50%;
  margin-right: -150px;
  float: left;
  position: relative;
  z-index: 0;
}

#middle_wrapper {
  width: 300px;
  margin-right: -150px;
  float: left;
  position: relative;
  z-index: 2;
}

#right_wrapper {
  width: 49.9%;
  float: left;
  position: relative;
  z-index: 1;
}